A large number of technical arrangements and methods are known for measuring and marking spatial points in the course of construction or development of buildings. In order to fulfill complex surveying tasks, in particular in a free terrain, geodetic total stations or theodolites, as known in the generic prior art, have been used for very many years. Such devices are, in principle, technically also suitable for fulfilling a plumb point finding functionality, for example during interior finishing of a building. However, they are technically relatively complex and costly devices, the operation of which is generally also too complex and complicated for a user not specifically trained in surveying technology, such as, for example, an artisan working in interior finishing of buildings.
For these reasons, an apparatus and a method for measuring uneven or planar surfaces of an open or closed space, for example of a room in a building, wherein a distance measuring device coupled to a theodolite is used, as proposed in FR 2 630 539, appear not to be very suitable for interior surveying of spaces that can be carried out in a simple manner.
In order to determine a plumb point and associated measuring and marking points in a building space, a conventional plumb bob is still used in many cases. In this context, the upper point of the plumb bob has to be able to be reached physically by a user, which can be difficult or even virtually impossible in high spaces (for example in high halls or church spaces).
In order to support conventional plumb point determination by means of a plumb bob or as an alternative to the use of a plumb bob, it is likewise known to use surveying devices based on emission of laser beams and reception of the reflection thereof from a spatial point provided as a plumb point. By way of example, such devices are designed and embodied in such a way that—after bringing the laser light source to a desired predetermined position—a perpendicular laser beam is emitted substantially in a self-centered fashion and, consequently, the spatial point situated perpendicularly directly above or below the predetermined position is indicated and/or marked by a laser beam.
DE 196 48 626 discloses a method and an apparatus for surface measurement with a laser distance measuring device comprising a laser transmitter and a laser receiver. The laser distance measuring device is mounted on a stand. The apparatus furthermore comprises a tilting and rotating device for alignment and distance measurement, a telescopic sight and also an electronic evaluation unit for angle data and distance data acquisition and data transfer to a computer. For measuring a space, the device is positioned at a central location in the space, from which all spatial and/or surface corner points to be acquired can be sighted by and exposed to the laser beam. In accordance with the disclosure in DE 196 48 626, the spatial points to be measured are in this case each sighted individually, if appropriate in the case of a relatively large distance with support of the observation by means of a telescopic sight. An automated sequential measurement of a plurality of spatial points, to be compared with a scan, for example, is not disclosed in DE 196 48 626. In particular, this document gives no indications whatsoever for possibilities concerning plumb point finding.
A similar apparatus and associated surveying method are disclosed in DE 195 43 299. This published patent application also reveals no indications with regard to an automated sequential measurement of a plurality of spatial points, comparatively with a scan, for example, and in particular no description concerning possibilities for plumb point finding.
A further similar apparatus and associated surveying method are disclosed in DE 44 43 413, the complementary published patent application DE 195 45 589 and WO 96/18083, which claims the priority of DE 44 43 413. They describe a method and an apparatus for measuring and marking on distantly situated lines, surfaces or in at least partly closed spaces. One or a plurality of relevant spatial points are measured according to in each case two solid angles and the distance relative to a reference location by means of a cardanically mounted laser distance measuring device. The laser distance measuring device can be pivoted about two mutually perpendicular axes equipped with goniometers. In accordance with one embodiment described in these documents, spatial points to be measured are selected manually and marking points are calculated from the measurement data, on the basis of a predetermined relative reference between measurement and marking, said marking points then being approached independently by the measuring and marking apparatus.
An embodiment for carrying out absolute measurements and markings is also disclosed, for which purpose a system leveling is carried out, which relates the mathematical model for calculating the spatial point coordinates in relationship to the actual directions in the space, whereby in principal it should also be possible to drop plumb lines in the space.
However, there is no disclosure of an automatically proceeding plumb point finding functionality on the basis of only one defined, first spatial point, and equally little disclosure of an automated sequential measurement of a plurality of spatial points, to be compared with a scan, for example.
Plumb point finding using relatively simple surveying devices based on laser measurement ensures a relatively large working or distance range with respect to a plumb point that is provided or to be remeasured, in association with relatively high accuracy. However, in accordance with the apparatuses known from the prior art, it is necessary to arrange the emission point of the laser precisely directly above or below the predetermined position for the spatial point provided as a plumb point, with exactly perpendicular alignment of the laser beam.
In the case of a relatively large distance between the laser and the sighted spatial point, the visual recognition thereof can be difficult. A further significant problem exists when the direct optical or visual link between the emission point and reception point of the reflected radiation is blocked, for example by objects situated in between with respect to the target point in the target direction. For plumb point measurement in such a situation, essentially, in accordance with the known teaching, only the use of complex surveying systems such as total stations or theodolites is appropriate, but this hardly seems advisable owing to the abovementioned technical complexity or economic outlay, or a very complex surveying method based on surveying systems mentioned above, for example with the measurement of additional spatial support points and the spatial correlation thereof by the operator, is appropriate, but this presupposes profound geometrical knowledge on the part of the user, which a user who is not relevantly trained generally does not possess and which would furthermore make the surveying process very complicated, in particular time-consuming.